Electric fence indicator



Oct. 28, 1947. 5, MOORE 2,429,764

ELECTRIC FENCE INDICATOR Filed Jan. 7, 1946 To GROUND I 2 HIGH LEAKAGE vINHCRENT CURRENT 3' uran me TYPE TRANSFORMER Patented Oct. 28, 1947UNITED STATES PATENT OFFICE 2,429,764 ELECTRIC FENCE INDICATOR Sidney A.Moore, Phoenix, Aria, assignor to The Prime Manufacturing 'Company,

Milwaukee,

Wis., a corporation of Wisconsin Application January 7, 1946, Serial No.639,604

3 Claims. (Cl. 1'77-311) This invention relates to electric fences'andin accordance with the conditions of soil and weather. In other words,for an electric fence controller to be fully satisfactory it must becapable of supplying a higher voltage than normal during exceedingly dryweather conditions and a lower voltage than normal in exceedingly wetweather conditions.

Experience has also shown that it is desirable to keep the voltageimpressed upon the fence wire at the lowest value consistent witheffectiveness. This follows from the fact that the danger of currentleakage resulting from poor insulators, weeds growing up against thefence wire and other causes, rises with increasing voltage. Thus,provision for adjusting the voltage impressed upon the fence wire by thecontroller is essential to a commercially satisfactory unit.

The development of the present day commercial electric fence haswitnessed a succession of efforts to devise a satisfactory indicator fordepicting the true condition of the fence wire, for unless the farmercan quickly ascertain the condition of the fence, it is not much use tohim. The indicator should tell him if the fence is in reliablecondition.

The first indicators consisted merely of small filament lamps connectedin series with the fence which indicated an electrical leakage conditionon the fence by lighting up. As the demand for more accurate indicationof the fence condition manifested itself, these early indicators gaveway to meter-type indicators, but these too were current-responsive and,therefore, unreliable as the fence-to-ground capacity affects thereading of a current responsive indicator. Variations in the length ofthe fence wire and its height from the ground result in variations infence-to-ground capacity. A large fence-to-ground capacity often causesconsiderable charging current to flow into the fence each time the fenceis periodically energized even though the fence is in perfectly goodcondition. Thus a current responsive indicator would indicate a leakagecondition when in fact the fence wassatisfactory.

Recognition of this deficiency of the current re- 'sponsive type ofindicator has recently led to the use of voltage responsive indicators,but even here complete satisfaction was not achieved, except in caseswhere the controller provided only a single out-put voltage, as theindicators were always connected between fence and ground. Being voltageresponsive it follows that a change in the voltage impressed upon thefence would result in a change in the indication afforded by theindicator.

Voltage responsive indicators of the type used in such installationsgenerally consisted of a bank of neon glow lamps connected in serieswith suitable resistance across each lamp so that the number of the glowlamps lighting up with each periodic energization of the fence wouldafford the desired indication of its condition. If such voltageresponsive indicators were employed in fence controllers having a numberof voltage taps on fence wire to a lower voltage tap would have the sameeffect as leakage on the fence with its consequent voltage reduction.The farmer, therefore, could not rely upon the number of lamps glowingas being a true indication of the fence condition. Adjustment at thecontroller to reduce the voltage impressed upon the fence, of necessitywould mean that a lesser number of the lamps would light up.

The disadvantage of this objectionable condition not only resided in theneed for checking the setting of the voltage regulator at the controllerbefore using the ratio of lit and unlit lamps as an indication for fencecondition, but also in the fact that on low voltage only one or twolamps were left to light up and indicate the entire range of the fenceconditions.

With a view toward overcoming all of these disadvantages of pastindicators employed in electric fences, it is a particular object ofthis invention to provide a fence condition indicator of the voltageresponsive type so connected in the circuit that regardless of thevoltage impressed upon the fence by the controller, the full range ofthe indicator will be available to show the true condition of the fence.

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed, and more particularly defined by the appended claims, it beinunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawing illustrates one complete example of thephysical embodiment of the invention constructed in accordance with thebest mode so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is a front elevatio-nal view of an electric fence controllerembodying this invention; and

Figure 2 is a schematic diagram of its component parts and theirconnections and showing this invention incorporated therein.

Referring now particularly to the accompanying drawing, the numeral 5designates a housing or cabinet within which the mechanism of thecontroller is mounted. As is customary, this housing has an insulatedfence terminal 6 and a ground terminal 7 mounted thereon. The bare fencewire (not shown) but Which as is customary, is supported off the groundby Posts carrying insulators, is adapted to be connected to the fenceterminal 6 while the ground terminal I is connected in any suitablemanner to ground.

Mounted on the front wall or panel 8 of the housing is an adjusting knob9 which controls a selector switch it] (see Figure 2). The setting ofthe knob 9 determines the voltage impressed upon the fence wire. Itscenter or intermediate position indicated by the letter N on a scale Hprovides voltage for normal weather conditions, Turning the knob to theleft to the position W connects the fence terminal 6 with a low voltagetap on the transformer secondary for wet weather conditions, whileadjustment thereof to the right to the position D connects the fenceterminal with a high voltage tap for dry weather conditions.

Also mounted on the front panel 8 of the housing or cabinet is a bank ofglow lamps indicated generally by the number l2. The specific manner inwhich these glow lamps are mounted in the cabinet being no part of thisinvention need not be described, suffice it to say that the lamps arearranged behind suitable window openings in the front panel.

As indicated in Figure 2, the transformer 13 is of the high leakage,inherent current limiting type, having a magnetic shunt built into it.Transformers of this type are customarily employed in A. C. fencecontrollers. It is a characteristic of such transformers that full shortcircuit current across any of its secondary taps results in zero voltageacross the entire secondary. In other words, the voltage across theentire secondary is inversely proportional to the current across any ofits taps.

One end of the secondary [4 of the transformer is connected to groundthrough the terminal 1. Its opposite end is connected to the highvoltage contact i5 of the selector switch 10. A mid-tap l6 connects withcontact ll of the switch, and a low voltage tap connects with theremaining contact l9 of the selector switch. Thus, depending upon thesetting of the selector switch, the voltage impressed upon the fencewire may be any one of three values. As a specific illustration, but notfor sake of limitation these voltages may be 1500 for dry weather andsoil conditions, 1000 for the normal voltage, and 600 volts for wetweather. The corresponding current for these voltages would be 20milliamperes, 30 milliamperes and 50 milliamperes.

The primary 20 of the transformer is adapted to be periodicallyenergized from a commercial A. C. power source represented by lines Lland L2 A timer mechanism indicated generally by the numeral 2| controlsthe periodicity of the energization and maintains it at approximatelyone per second. Such timing mechanisms are, of course, well-known andconsequently detailed description is not required.

The primary circuit also includes a control unit indicated by number 22and which embodies a radio interference suppressor and an automaticcut-out unit as shown in Patent Re, No, 22,143, issued July 21, 1942, toJ. E. Vaughan for Electric fence.

The indicator l2 consists of a bank of neon glow lamps 23 connected inseries across the en tire secondary of the transformer, a calibratingresistor 24 preferably being incorporated in this series connection. Inaddition, a resistor 25 is connected across each glow lamp 23. Thevalues of these resistors are progressively greater so that a reductionin the voltage across the series conected lamps reduces the number oflamps that light up each time the fence is energized. Thus as leakage onthe fence increases and the voltage across the secondary dropsproportionately, the number of glow lamps lighting up decreases. Ifthere is no leakage on the fence, all of the glow lamps will light upwhether the fence is connected to the high, low, or medium voltage tap.If a leakage condition has reduced the efficacy of the fence by fiftypercent for a given applied voltage, one-half the lamps will light up nomatter which of the selected voltages it happens to be. In other wordsthe number of glow lamps which light up is the same for a givenpercentage of leakage regardless of which one of the secondary taps isconnected with the fence wire.

Inasmuch as the probability of leakage on an electric fence, and forthat matter any current carrying conductor, increases as the voltageapplied thereon is increased, it follows that the percentage of leakageis a function of the applied voltage. Thus, for instance, with anapplied voltage of 1,000 volts (obtained in the present instance withthe voltage selector switch at normal), leakage of about forty thousand(40,000) ohms would decrease the efficacy of the fence to aboutseventy-five percent of its full capability to give an animal a shock.In other words, there would be approximately twenty-five percent (25%)leakage on the fence.

Under such conditions the fence still would be capable of giving ananimal an effective shock and the farmer would know this because threeof the four glow-lamps would be lighting up with each energization ofthe fence.

If the voltage selector switch was turned to, or happened to be in itshigh voltage position so that the applied voltage was 1500 volts, andassuming the same condition of the fence, the increased voltage in thisinstance would raise the percentage of leakage to about seventy-fivepercent (75%) leaving the fence only one-fourth effective. This is notsufficient and the farmer would be advised of the deficiency by the factthat only one of the four glow-lamps would be lighting,

On the other hand, if the voltage selector switch was in its low voltageposition so that 600 volts were being applied to the fence, the sameleakage, that is forty thousand (40,000) ohms, would not materiallyreduce the efficacy of the fence. In this case the percentage of leakagewould be so slight that all of the four glow-lamps would continue tolight up, thus telling the farmer that the shock upon the fence wasentirely satisfactory.

Of course, inasmuch as the voltage selector switch should be set tocorrespond with weather conditions, the farmer would not turn it down toits low voltage wet Weather position, or even to its medium voltage,normal position, if the ground and weather were extremely dry. Anindication of leakage under such dry weather conditions would be areliable indication that the fence needed prompt attention. It wouldmean a broken wire or other such serious condition, for the probabilityof serious leakage at the insulators or from weeds is slight in real dryweather.

Where weather conditions would permit, the farmer might very well reducethe voltage impressed upon the fence by merely adjusting the selectorswitch 9 and thus restore the efiicacy of the fence, assuming theindicator had registered a deficient fence at a higher voltage beingapplied at the time the deficiency was noticed. It follows, therefore,that the indicator of this invention serves not only to show the farmerthe true condition of the fence (that is, its ability to give an animala shock) regardless of which of the secondary taps the fence isconnected with; but it also serves to educate the farmer out of themistaken belief that his fence will be improved by increasing thevoltage applied thereon.

The apparent anomaly of the fence bein better able to give an animal ashock if the voltage is reduced, is explained by the fact that anelectric fence is seldom is ever adequately insulated from ground. Eventhough the fence is free from contact with weeds and is otherwise ingood condition, the leakage path between the tie wires by which thefence wire is held to the supporting insulators and the heads of thenails holding the insulators to the posts usually is only three eighthsto one-half an inch. This short leakage path, duplicated at eachinsulator, makes some leakage inevitable, except in very dry weather,and of course as the voltage is increased, the percentage of leakagerises.

For purposes of illustration but not limitation, the specific values ofthe resistors employed in the indicator network may be as follows,reading from bottom to top in Figure 2: 25 M ohms, 60 M ohms, 150 Mohms, 500 M ohms and the calibrating resistor 24, 100 M ohms.

From the foregoing description taken in connection with the accompanyingdrawing, it will be readily apparent to those skilled in this art thatthis invention achieves what the industry has been seeking sinceelectric fences came into commercial use, namely an indicator whichactually and truly depicts the leakage condition of the fence regardlessof the voltage being impressed thereon by the controller.

What I claim as my invention is:

1. Means for indicating the effectiveness of an electric fence having abare fence wire connected with one of a plurality of taps on thesecondary of a transformer having its primary suitably energized andadapted to provide an open circuit voltage to the fence wire of a valuedepending upon the secondary tap with which the fence wire is connected,said transformer being of the high leakage, inherent current limitingtype so that full short circuit current across any of its secondary tapsresults in zero voltage across the entire secondary, comprising: a bankof glow lamps; means electrically connecting the glow lamps in seriescircuit across the entire secondary of the transformer; and a pluralityof resistors, one connected across each of said glow lamps, saidresistors being of progressively greater resistance values so that areduction of the voltage across the glow lamps decreases the number oflamps that light up with each energization of the fence wire, the highleakage, inherent current limiting characteristic of the transformerassuring that the voltage across the glow lamps is inverselyproportional to the percentage of leakage on the fence, so that thenumber of glow lamps lighting up when the fence wire is energizedindicates the percentage of leakage of the applied voltage regardless ofwhich one of the secondary taps the fence wire is connected with.

2. In an electric fence, the combination of: a high leakage inherentcurrent limiting type transformer having a plurality of taps on itssecondary; means for connecting the fence with any one of the secondarytaps so that the voltage applied to the fence may be selected to bestsuit different weather and soil conditions; a bank of glow-lamps; meanselectrically connecting the glow-lamps in series circuit across theentire secondary of the transformer; and a plurality of resistors, oneconnected across each glowlamp, said resistors being of progressivelygreater resistance values so that a reduction of the voltage across theseries of glow-lamps decreases the number of glow-lamps that light upwith each energization of the fence; the high leakage inherent currentlimiting characteristic of the transformer assuring that the voltageacross the glow-lamps is inversely proportional to the percentage ofleakage on the fence, so that the number of glow-lamps lighting up whenthe fence is energized indicates the percentage of leakage of theapplied voltage regardless of which one of the secondary taps the fenceis connected with.

3. In an electric fence, the combination of: a high leakage inherentcurrent limiting type transformer having a plurality of taps on itssecondary; means for connecting the fence with any one of the secondarytaps so that the voltage applied to the fence may be selected to bestsuit different weather and soil conditions; a voltage responsiveindicator comprising a plurality of voltage responsive devices, each ofwhich is responsive to a different voltage; and means connecting saidvoltage responsive indicator across the entire secondary; said indicatordevices each constituting display means and together depictingpercentage of change from a predetermined voltage across the entiresecondary; the high leakage inherent current limiting characteristic ofthe transformer assuring that the voltage across the entire secondary,and thus across the indicator, is inversely proportional to thepercentage of leakage on the fence, so that the depiction afforded bysaid display means at all times shows the percentage of leakage of theapplied voltage regardless of which one of the secondary taps the fenceis connected with,

SIDNEY A. MOORE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,249,696 Pfanstiehl July 15,1941 2,304,954 Pfanstiehl Dec. 15, 1942 2,398,442 Moore Apr. 16, 1946

